Sure, he may not be able to have dual ultra 13's but and watch independence day 24-7 but with a little investigation and consideration he can get Im sure he can get satisfying surround sound...
A sub turned back a little {dual smaller subs may be less noticeable down stairs}, an isolation pad under the sub(s), butt kickers installed in the seating, asking the neighbors if they can hear it or are bothered by it, and not playing the subs during certain times, like 3 am on a monday night may not be a great idea....
If you ask me, having close neighbors is just a speed bump not a stop sign... I am lucky to have neighbors so far away that I would need to install a dozen 21' PRO SUBWOOFERS at the property line facing their home before they hear it if they are outside listening for it, lol.... But if I were you I wouldn't go moving yet, just do some recon and figure out what will work and how much of it...